Various technologies having a purpose of supporting making an electronic mail or providing detailed information of an electronic mail is being known.
Japanese Patent Application Publication No. 5-204795 (hereinafter referred to as Document 1) discloses a technology in which a tree diagram of office information is shown and a user is designated as a destination from the tree diagram in order to prevent a person making an electronic mail and sending the electronic mail (hereinafter referred to as a sender) from designating an erroneous destination. Japanese Patent Application Publication No. 11-24880 (hereinafter referred to as Document 2) discloses a technology in which a member recorded in a mailing list is shown to a receiver of a mail sent to the mailing list, and the receiver is informed of another receiver except for himself or herself.